By using in situ observation data (from stations including 288 island stations, 380 onshore stations, 28 float buoys, 37 ship-board stations, 53 meteorological observation towers, 13 drilling platforms stations, and 9 wind profilers) and sounding data, gales with wind force of 6 or above in China offshore area from 2010 to 2014 were analyzed by taking use of the method of synoptic meteorology. According to the weather systems on the ground, synoptic patterns of the gales can be divided into 3 classes:cold air, extratropical cyclone, and tropical cyclone. The cold air class can be divided into three types: small trough moving eastward, small trough development, transversal trough changing to the vertical. The extratropical cyclone class can also be divided into three types: the East China Sea cyclone, the Bohai and the Yellow Sea cyclone, Mongolia cyclone. These pattern classifications can provide reference of synoptic meteorology background for forecasting and warning of offshore gales of China.